﻿/*
 * Copyright 2012 The Netty Project
 *
 * The Netty Project licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 *
 * Copyright (c) The DotNetty Project (Microsoft). All rights reserved.
 *
 *   https://github.com/azure/dotnetty
 *
 * Licensed under the MIT license. See LICENSE file in the project root for full license information.
 *
 * Copyright (c) 2020 The Dotnetty-Span-Fork Project (cuteant@outlook.com) All rights reserved.
 *
 *   https://github.com/cuteant/dotnetty-span-fork
 *
 * Licensed under the MIT license. See LICENSE file in the project root for full license information.
 */

namespace DotNetty.Common.Utilities
{
    using System.Collections.Generic;

    public interface IHashingStrategy<in T> : IEqualityComparer<T>
    {
        int HashCode(T obj);
    }

    public sealed class DefaultHashingStrategy<T> : IHashingStrategy<T>
    {
        public int GetHashCode(T obj) => obj.GetHashCode();

        public int HashCode(T obj) => obj is object ? this.GetHashCode(obj) : 0;

        public bool Equals(T a, T b) => ReferenceEquals(a, b) || (a is object && a.Equals(b));
    }
}
